Mechanical coin-acceptor units are generally known, reference is made for example to U.S. Pat. No. 4,545,474 in which a mechanical coin-acceptor unit is mounted on a front plate arrangement. This coin-acceptor unit has a first and a second coin track, an opening being present between them. In this known arrangement, a shoulder or a stop member is situated in the first coin track, onto which an inserted coin rolling in the running direction impacts, then tilts to the side and continues its path further on the offset first coin track and if necessary is directed through the opening into the second coin track. Such a shoulder or step serves normally as manipulation protection in order that for example a wire introduced into the coin slot aperture or another tool cannot destroy the checking devices of the mechanical coin-acceptor unit.
It has been shown that such a shoulder does not function with any arbitrary coin slot arrangements, for example it can occur that an inserted coin, which falls on the shoulder, remains there. This prevents a friction-free function of the coin-acceptor unit.